The three Japanese scientists who invented the first efficient Blue LEDs in the mid 1990s have received the 2014 Nobel Prize in Physics. The invention of efficient blue LEDs was a foundational step in the creation of the bright white LED lights being produced by the likes of Cree and Philips, which are driving the most significant transformation in lighting technology since the invention of the incandescent bulb. Isamu Akasaki, Hiroshi Amano, and Shuji Nakamura will share the 8 million Swedish krona prize (~$1.1 million).
As you probably know, we’ve had red and green light-emitting diodes (LEDs) for a long, long time — but blue LEDs, for a variety of reasons, had evaded our scientists until fairly recently. This is why all of your old gadgets — TVs, VCRs, modems — were adorned with red and green LEDs… until out of nowhere, at the end of the ’90s, blue LEDs were suddenly everywhere. The overuse of bright blue LEDs is a bit obnoxious in my opinion, but after some 40 years of using just red and green I can understand why device makers were suddenly keen to put blue LEDs on everything.
The Nobel committee singled the trio out for “revolutionary” invention which “has already contributed to create white light in an entirely new manner to the benefit of us all.”
LEDs are very simple devices, essentially consisting of a single piece of semiconducting material — like gallium arsenide (GaAs) — that has been doped to create a p-n junction. When electricity is applied to this p-n junction, electrons rush to fill any electron holes, releasing energy in the form of photons (light). The exact frequency of the light (i.e. the color) is dictated by the bandgap of the p-n junction (i.e. how much current is required to jump the gap). Thus, by changing the semiconducting material — and thus changing the bandgap — different color LEDs can be created.
Later work including indium-gallium-nitride (InGaN) quantum wells improved efficiency yet further and allowed for tuning of the light frequency. And now… well, as you know, there has been an explosion in both blue LEDs and, more importantly, white LEDs.
“White LED lamps emit a bright white light, are long-lasting, and energy-efficient,” the committee said. “They are constantly improved, getting more efficient with higher luminous flux (measured in lumen) per unit electrical input power (measured in watt).
It’s pretty awesome that a single invention — the humble blue LED — single-handedly triggered a revolution in lighting. But hey, that’s why Nakamura, Amano, and Akasaki are being awarded a Nobel Prize. “The invention of the blue LED is just twenty years old, but it has already contributed to create white light in an entirely new manner to the benefit of us all,” says the Nobel Committee in Physics. “[Due to low power requirements] the LED lamp holds great promise for increasing the quality of life for over 1.5 billion people around the world who lack access to electricity grids.”
